Topic: Kibblewhite valve springs installed height - CB400F

[sweetkev]

Anyone using Kibblewhite valve springs on their CB400F?  Did you have to remove material from the spring seats to achieve the correct installed height?

Specified spring installed height on the package is 1.270, but I'm measuring ~1.180 between bottom of retainer and top of valve base washer on my head.

I wouldn't sweat it if it was only .010 or so off, but I'm out by almost a tenth of an inch.  I've reached out to Kibblewhite to confirm the installed height printed on the package is correct, just figured I'd consult the hive-mind as well.

Thanks much.

[MRieck]

I'm a bit surprised you came up that short especially if a valve job was done. What valves are you using? I have several sets on 400F springs coming my way from Kibblewhite....should be here early next week. I can measure the spring pressure at .270 and .180 and let you know. I'll check coil bind too.

[sweetkev]

Thanks, lucky break you've got some on the way already!

They appear to be the stock valves, although I don't know for sure.  I've only measured 1 intake valve so far, I'll measure a few more to confirm the measurement but I can't see why they'd be much different.

Appreciate your help, thanks again.

[Don R]

 I had wondered about my APE CB750 springs once. The consensus was, just put them in. My race car had problems with the cam and springs. I was getting about 15 miles from new ones before they began to fail. That's why I worried. They have been fine.

[Kevin]

I have them installed in a couple of mine with no issues.

Sent from my SM-N960F using Tapatalk

[MRieck]

OK....just checked everything. Spring pressure @ 1.270 is only 35 lbs. Pressure @ 1.180 is 51 lbs.....much, much better. I have a feeling Kibblewhite has a typo.....I have seen it with the CB750 5mm conversion kit and it took years to get corrected. So.....1.180 seems very good to me and you can run a cam up .420 lift ....probably more but I think they don't exist.

[gschuld]

OK....just checked everything. Spring pressure @ 1.270 is only 35 lbs. Pressure @ 1.180 is 51 lbs.....much, much better. I have a feeling Kibblewhite has a typo.....I have seen it with the CB750 5mm conversion kit and it took years to get corrected. So.....1.180 seems very good to me and you can run a cam up .420 lift ....probably more but I think they don't exist.

Mike,

For cb750 cams, lift over .420” exists but they are far from mainstream.  The Megacycle 125x12 with .430/.445 is one and the KH super duper .457/.457 cam with oversized base circle is an especially extreme one.

George

[MRieck]

George....I was referring to the 400F cams. The highest lift from Megacycle is .290 on the intake side.

[gschuld]

Ah, that makes sense. 

I get confused easy…🙄

George

[sweetkev]

OK....just checked everything. Spring pressure @ 1.270 is only 35 lbs. Pressure @ 1.180 is 51 lbs.....much, much better. I have a feeling Kibblewhite has a typo.....I have seen it with the CB750 5mm conversion kit and it took years to get corrected. So.....1.180 seems very good to me and you can run a cam up .420 lift ....probably more but I think they don't exist.

Thanks a lot for checking.  Did your package have that same 1.270 figure printed on it?

[MRieck]

OK....just checked everything. Spring pressure @ 1.270 is only 35 lbs. Pressure @ 1.180 is 51 lbs.....much, much better. I have a feeling Kibblewhite has a typo.....I have seen it with the CB750 5mm conversion kit and it took years to get corrected. So.....1.180 seems very good to me and you can run a cam up .420 lift ....probably more but I think they don't exist.

Thanks a lot for checking.  Did your package have that same 1.270 figure printed on it?

Yes......1.270